Conventionally, such a packaging machine is constructed in such a manner that a cylindrical film pouch can be conveyed while maintaining its cylindrically inflated state so that contents such as cakes can be filled therein. In order to perform such a conveying process, a pair of timing belts is disposed along the conveying direction of the cylindrical film pouch, and these timing belts are formed with suction holes so that a negative pressure is applied in order to suck and inflate the cylindrical film pouch. As a timing belt provided with suction holes, one disclosed in Patent Document 1 is known, in which the suction holes are formed in a flat area of the central portion of the timing belt, in which belt teeth are not formed, for example.
PATENT DOCUMENT 1: Unexamined Utility Model Publication No. (HEI) 7-38021